The present invention relates generally to exercise equipment and more particularly relates to weightlifting machines.
It is known that in order to accomplish an increase in the strength and/or mass of a muscle, the muscle must generally be overloaded. The most common way to achieve muscle overload is through repetitive lifting of weights, sometimes referred to as resistance training. Weight lifting machines are commonly used in resistance training, where the amount of weight is fixed at an amount less than the weightlifting capacity of the weight-lifter. As the weight-lifter progresses through his repetitions, the muscles eventually fatigue. The muscles generally reach their capacity only during the last few repetitions. Thus, several sets of repetitions can be necessary for appropriate muscle building, making the first few repetitions wasteful.
As used herein, xe2x80x98weightlifter""s capacityxe2x80x99 and xe2x80x98weightlifting capacityxe2x80x99 generally refers to the maximum amount of weight a weight-lifter can lift, once, on a given weightlifting machine, before muscle fatigue prevents another repetition of the same amount of weight. A weightlifter""s muscles are generally overloaded when the weightlifter exceeds capacity. By slightly exceeding capacity, and just entering muscle overload, a weightlifter may only complete a partial repetition while generally maximizing the strengthening of the muscle.
Attempts to reduce or eliminate the initial, inefficient repetitions employ systems that begin at a weight at the weightlifter""s capacity, and reduce the amount of weight throughout the exercise. This can be achieved, for example, by having assistants remove weights in ten to twenty-five pound decrements as a weight-lifter is performing the exercise. However, each decrement is not likely to correspond with the weightlifter""s reduced capacity due to the muscle fatigue caused by the previous repetition. Further, the awkwardness, potential dangers and inefficiency of this procedure are apparent to the person skilled in the art.
Another attempt to vary the weight during conventional weight training is found in U.S. Pat. No. 4,531,727 to Pitre. Pitre teaches a weight training machine in which a tension line is attached to a vessel filled with a fluid, which provides resistance when pulled at the opposite end by a weight-lifter. During the course of the exercise, the fluid drains from the vessel and the weight is reduced. Unfortunately the weight training machine of Pitre is comprised of a complex, somewhat awkward system, with an overall unfamiliar structure that radically varies from conventional weight lifting machines. Although Pitre can provide a more efficient workout, it is believed that the unfamiliar structure of the machine in Pitre can lead to a consumer reluctance to change from conventional weightlifting machines to the machine taught in Pitre. Additionally, gymnasiums using the Pitre machine must purchase an entire machine, thus increasing cost and occupying valuable floor space.
Another disadvantage with Pitre is that the fluid in the vessel drains to near empty during the exercise, which can undershoot the weightlifter""s capacity during the final repetitions. Further, the decrement may not correspond with the weightlifter""s capacity. By the same token, the vessel in Pitre is awkward to fill to the weightlifter""s capacity. Thus, a weightlifter using the machine taught in Pitre does not necessarily maximize the fill efficiency of his workout. It will also be apparent that particularly strong weightlifters will require very large fluid vessels, making the machine even more awkward.
Other prior art include U.S. Pat. No. 5,842,957 to Wheeler and U.S. Pat. No. 4,531,727 to Eckler. Wheeler teaches a hollow dumbbell filled with water that reduces in weight throughout the course of the exercise as the water drains. However, the wheeler was designed primarily to be used in conjunction with bodies of water, as the dumbbell must be submerged in water to be filled prior to each use. Additionally, the reduction in the weight of the dumbbell was designed to make it safer to put down after the exercise, and does not teach flow rates to produce a more efficient workout. Eckler teaches fluids in a hydraulic system to produce a more efficient workout through isodynamic resistance. Although Eckler can incorporate a system to select different weight training modes, none achieve a reduction in the amount of weight throughout the course of the exercise. Additionally, the use of hydraulic fluids can be expensive, environmentally unfriendly and entail additional maintenance.
It is therefore an object of the invention to provide a novel weight lifting apparatus which obviates or mitigates at least one of the disadvantages of the prior art.
A device for retrofitting onto or incorporating into a conventional weightlifting machine is provided. The device includes a charge tank and a load tank and a set of hoses for communicating fluid between the tanks. The load tank rests places or supplements a number of weights in a conventional weight stack, while the charge tank rests on the floor proximal to the weightlifting machine. A fluid control means is provided for alternatively filling the load tank with water stored in the charge tank and draining the fluid back into the charge tank from the load tank, as desired. Before an exercise, the weight stack is set to a base load and the load tank is filled with water using the fluid control means. During the exercise, the fluid control means is set to allow water to drain back into the charge tank. The flow rate is set to drain the load tank, either manually or automatically, so that the weight-lifter is lifting a desired amount of weight during each repetition. Preferably, the flow rate, in pounds per minute, is proportional to the muscle fatigue of the weightlifter.
In another embodiment of the invention, a method is provided for performing weight training, comprising the steps of:
performing an initial repetition at a first predetermined weight, the first predetermined weight being the capacity of a weight lifter during the initial repetition; and
performing at least one additional repetition at a second predetermined weight less than the first predetermined weight, the second predetermined weight being substantially equal to a reduced capacity of the weight lifter, the reduced capacity resulting from muscle fatigue due to a previous repetition.